Terebellida unique characters : Polychaeta with first segment without chaetae, with a gular membrane, with a heart body, with either multiple grooved feeding palps or a single pair of grooved feeding palps.
Terebellida extended diagnosis: Head somewhat fused with anterior segments, or retractile, and is not distinct. Head appendages variously surround the mouth and include from a single pair of shortish palps to very numerous, long, contractile and flexible feeding tentacles (multiple palps), and also simple or branched gills. Pharynx unarmed and not eversible. Parapodia without lobes but chaetae may be raised on ridges. Both notochaetae and neurochaetae may be capillaries or uncini. Notochaetae may be absent posteriorly. Compound neurochaetae may be present in Flabelligeridae. Anterior chaetae may be conspicuous projecting paleae. In Sternaspidae chaetae are lacking except for anterior spines and posterior bundles of capillaries.
Terebellida remarks: Families Alvinellidae, Ampharetidae, Pectinariidae, Terebellidae, Trichobranchidae comprise the traditional Terebellida with multiple palps. The Cirratuliformia families Acrocirridae, Cirratulidae, Fauveliopsidae, Flabelligeridae, and Sternaspidae also now included. The Terebellida are mostly selective particulate feeders.
Unique character summary modified after Rouse, G.W.; Pleijel, F. (2001). Polychaetes. Oxford University Press, Oxford. 354 p.
Last modified by G. Read, 21/07/2003 (dd/mm/yy)